1. Field of the Invention
The present invention relates to an apparatus for monitoring the spring force exerted by a spring actuated bar coupled to a cable clamp designed for chair lifts and cable cars, wherein reference springs representing the minimum clamping force act to displace the actuator spring whenever the spring force exerted by the spring actuator falls below the minimum clamping force to be monitored, thus releasing a trip latch, whereby the springs of the spring actuator are compressed on thrust ram (2) which bears at one end on clutch lever K and on the other end on cable clamp S.
2. Description of the Prior Art
The spring force exerted upon a clutching cable clamp must be precisely monitored for reasons of technical safety. Various means of achieving this are known. However, one can distinguish between two basic systems: those in which the force exerted by the cable clamp is monitored with the clamp released and those in which the force of the cable clamp is monitored with the clamp applied. The present invention is of the type in which the force exerted by the clamp is monitored while the clamp is applied.
One device for monitoring the spring force exerted by a spring actuator currently available on the market, operates with a number of reference springs which represent the preset force. As soon as the force exerted by the cable clamp actuator spring falls below the preset value, the mobile part of the cable clamp is displaced towards the fixed part of the clamp, thus releasing a trip catch.
One of the disadvantages of this existing apparatus is that monitoring of the force exerted by the actuator spring is performed by a multiplicity of symmetrically arranged springs which may themselves be subject to failure. A further disadvantage is that if a spring plate of one of the actuator springs should fail, the resulting displacement is minimal and would not always suffice to insure positive release of the trip latch.